Docker로 ubuntu 컨테이너를 생성하고 ubuntu컨테이너에 접근하여 #apt-get update 명령어를 했을때 더보기 # apt-get update Hit:1 http://archive.ubuntu.com/ubuntu focal InRelease Get:2 http://security.ubuntu.com/ubuntu focal-security InRelease [114 kB] Get:3 http://archive.ubuntu.com/ubuntu focal-updates InRelease [114 kB] Get:4 http://archive.ubuntu.com/ubuntu focal-backports InRelease [108 kB] Reading package lists... Done E: R..